Questions tagged [swap]
Linux divides its physical RAM (random access memory) into chucks of memory called pages. Swapping is the process whereby a page of memory is copied to the preconfigured space on the hard disk, called swap space, to free up that page of memory. The combined sizes of the physical memory(RAM) and the swap space is the amount of virtual memory available. Linux has two forms of swap space: the swap partition and the swap file.
344
questions
6
votes
1
answer
6k
views
Why does host swap out VMs when there are 16GB of buffer cache and swappiness = 0? [duplicate]
I have a desktop running Ubuntu Quantal using OpenStack Folsom on an Intel i5 with 32 GB RAM and 2 GB swap. I'm running 7 VMs each sized like a EC2 m1.small, so 1.7 GB RAM each. I'm using KVM.
As I ...
- 539
2
votes
2
answers
2k
views
Linux process swap usage is greater than the overall system swap usage
I have a strange problem that when I run top command it shows that some processes are using around 1.5GB of swap space but then the overall usage of the system swap is way to less to something around ...
- 83
2
votes
1
answer
99
views
Is there a way to free swap?
After using vmware player with some virtual machine, it seems like my swap stays quite occupied and it doesn't changes unless i reboot it.
However, regularly swap is not used much by other ...
- 402
2
votes
2
answers
3k
views
Ubuntu: forcing processes into swap, or into RAM
I am now solving the following problem on Ubuntu: Is it possible to specify if one process should run only in the RAM (i.e. is not allowed to swap) or reversely only in the swap part? I mean that the ...
- 21
22
votes
3
answers
20k
views
How to disable swap files in ESXi?
We are running a few Solaris / Linux VMs on ESXi that contain very sensitive encrypted data that eventually get decrypted as required in memory.
Everything is fine, except for the ESXi swap files ...
- 331
1
vote
1
answer
2k
views
How to instruct linux not to swap out hot pages of mmaped files?
I have a server where I run worker processes that mmap serveral rather big read-only "dictionary" files (~8GB total). Tests showed that they actively access only around ~1GB worth of the pages in ...
0
votes
1
answer
108
views
Swap files in Cloud Infrastructures
At our company we set up an OpenStack Cloud and are currently creating internal guidelines for creation of OS templates / images. One controversial topic was if we should provide swap inside the VM ...
- 251
3
votes
1
answer
2k
views
Limiting memory usage and minimizing swap thrashing on Unix / Linux
I have a few machines that I machine that I use for running large numbers of jobs where I try to limit the number of jobs so as not to exceed the available RAM of the machine. Occasionally I mis-...
- 255
2
votes
1
answer
4k
views
How much RAM do I need to run a forum using Nginx, Gunicorn, Django?
I started an ec2 instance (micro) to test the amount of memory I have available to run a website but I was expecting having a bit more. So my question would be: How much RAM do I need to run a site ...
- 121
1
vote
2
answers
162
views
How can I determine the method of this DDoS attack? [duplicate]
My server went down earlier - looks like a DDoS. A spike in traffic to around 13mbit, the swap goes from idle to maxed in about 5 minutes, and server stops responding.
I would like to protect ...
- 167
0
votes
1
answer
469
views
how do OS deal with dirty page if there is no swap space [closed]
As in text books OS will move dirty pages to swap space based on LRU algorithm and make space for new process in RAM.
But how do OS do this if there is no swap.
- 37
4
votes
1
answer
189
views
Is it sensible to use SLC swap as a RAM substitute on a VM host?
I have a few oldish servers running virtual machines but they are limited to 16GB RAM and that limits the number of VMs I can run and the options for RDS.
I've added a RAID1 array of two Intel 311s: ...
user83664
0
votes
1
answer
5k
views
Very high Magento/Apache memory usage even without visitors (are we fooled by our hosting company?)
I am no server guy and we have issues with our speed so I come here asking for advise. We have a VPS with 2 cores and 2gb of RAM at a Magento specialized hosting company. Over the course of the last ...
1
vote
1
answer
299
views
Swap space maxing out - JVM dying
I have a server running 3 WordPress instances, MySql, Apache and the play framework 2.0 on 64m initial & max heap. If I increase the max heap of the JVM that play is running in even by 16m I see ...
- 206
0
votes
1
answer
784
views
how can I tell if there is a cpu trashing on my linux machine
I want to write a script that will kill my processes when my machine is doing "too much" swapping of process memory from disk to memory.
What is the best way to determine that? I saw top has %wa and ...
- 109
10
votes
2
answers
38k
views
How is htop "Swp" calculated?
When I run htop (on OS X 10.6.8), I see something like this :
1 [||||||| 20.0%] Tasks: 70 total, 0 running
2 [||| 7.2%] Load average: 1.11 0....
- 203
11
votes
3
answers
14k
views
Using tmpfs + a very large swap partition for /tmp instead of a regular filesystem?
I have Linux server and I have a spare 500GB disk partition. I wanted to format it and use it for /tmp. The server occasionally runs some large data processing tasks so it can happen that /tmp will ...
- 635
6
votes
3
answers
6k
views
Should I use swap in KVM guest?
Now I'm trying to create KVM templates with CentOS and I'm not sure should I create swap partition on guest OS or not. In future it will be lot's of small VPS with 256-1024Mb RAM and if swap partition ...
- 279
4
votes
2
answers
5k
views
How to read `top`. Process list says processes have swap but overview says no swap is being used
I am using top to monitor my server. The swap row reads
Swap: 1044220k total, 0k used, 1044220k free, 148544k cached
I have hit O p to sort by swap.
PID USER PR NI VIRT RES ...
- 201
4
votes
2
answers
26k
views
Linux cached memory: Over 85% of cached memory and using swap
I read about Linux and cachd memory at linuxatemyram but there is something that doesn't make sense to me, if the server have even a low load, instead of freeing some cached memory it starts using ...
- 449
4
votes
3
answers
4k
views
Disadvantages of a large swap partition
I'm aware that there is a huge performance decrease when using swap memory, but if you have wasted hard drive space is there any disadvantages to having (hopefully not using) a large swap partition?
- 466
3
votes
2
answers
3k
views
Why is my KVM, RHEL6.2 server swapping?
I have a RHEL6.2 server that I'm using to run KVM virtual machines.
The server itself has 16 GB of RAM. I want to see the biggest VM I can run on it and not let the qemu-kvm process swap. The VM ...
- 221
0
votes
1
answer
2k
views
My server is running out of memory, despite having all swap free
I am using Debian 6 (Squeeze). The server has 4gb of memory in it, and 8gb of swap. I'm starting to get memory alloc errors at high application load times, but from top command:
Mem: 4055944k total,...
- 265
4
votes
1
answer
343
views
How to lock a process in RAM (make it unswapable)
Is there a way to instruct the kernel (Linux kernel) to never swap a certain process that has already been started?
- 143
0
votes
1
answer
189
views
CentOS - Convert swap memory to regular?
Take a look at this screenshot that I took after doing free -m: http://gyazo.com/aa54d264956e56acb99024e2374de0c0.png?1340387738
I notice that I have a ton of swap memory not being used, could I ...
- 103
1
vote
2
answers
1k
views
Maximum swap file size
I'm doing some file processing that seems to require an enormous swap file: even 20Gb isn't enough. What's the theoretical maximum? Running swapon on a 1Tb file resulted in:
swapon: /mnt/big/swap....
- 5,910
-4
votes
1
answer
102
views
How to control the memory usage of a swap partiotion? [closed]
Thats pretty much the quesiton: how can I control the memory usage of each swap partiotion, say /etc/sa5?
- 3,157
14
votes
1
answer
15k
views
How do I enable swap file on my server?
I've followed this
but when I run:-
#swapon /swapfile1
I get::-
swapon: /swapfile1: swapon failed: Operation not permitted
The system is extremely slow with 1GB of RAM trying to run GUI +...
- 177
0
votes
4
answers
197
views
On a virtual Linux system where storage is on network what's the point of the swap file? [closed]
The Linux servers are running on some VMWare ESX systems (guessing, I'm just user). These systems don't have the disks directly attached: they perform everything on a virtual disk that is actually a ...
- 121
0
votes
3
answers
3k
views
With Xen, when is Swap used?
I have a 512MB Xen VPS with 1024MB Swap.
When I SSH into it and type "free -m", it shows I have around 50MB free memory.
I had recently downgraded from a 1024MB plan because I didn't need the memory....
- 5
0
votes
1
answer
1k
views
LVM cannot detect my swap or '/' volume group but why is the swap still present
i have a server (hp x86 blade running OEL/RHEL5) that has a faulty lvm filter configured in lvm.conf
filter = ["a|^/dev/emcpower.*|", "r/.*/"]
we also use cciss devices so there should have been an ...
- 125
1
vote
3
answers
1k
views
I/O rate and CPU Eating up Server making terribly slow site
My server (Ubuntu 10.04 Lucid LAMP Stack) on linode (1024MB ram, 40 GB storage, 400 GB Transfer) is loading terribly slow. My site (WordPress) is relatively small (1.5 Gigs of mysql) and gets around ...
- 163
3
votes
1
answer
604
views
Force process pages to get unswapped
I started 4 processes doing heavy computations. The machine has 4 full cores, and each process is single-threaded, so they don't compete for CPU. However I realized that they require more memory than ...
- 767
14
votes
3
answers
14k
views
Ubuntu Linux: Process swap memory and memory usage
My Ubuntu eats more memory than the task manager is showing:
sudo ps -e --format rss | awk 'BEGIN{c=0} {c+=$1} END{print c/1024}'
2750.29
free -m
total used free ...
- 271
5
votes
1
answer
745
views
Mysterious swap usage on EC2
We're in the middle of a project to move our infrastructure from a co-lo situation into Amazon EC2 and we've noticed some weird memory characteristics of the processes in our setup. Without going into ...
- 163
1
vote
1
answer
3k
views
Centos server not using SWAP properly and getting OOM
Recently I've been having some serious memory issues with my server. Just the other day, my server became completely unresponsive, and oom-killer started killing services at random (httpd, php, etc). ...
- 93
6
votes
5
answers
4k
views
What happens if you run out of RAM and swap?
Running MySQL on a box with 32 gigs of RAM. Swap is 99% full, and there is about 200 MB of RAM free. MySQL is the culprit of course. What happens when both RAM and swap are completely filled? Thanks!
- 2,293
4
votes
1
answer
758
views
Apache is not using SWAP and it's reporting page allocation failure
Check the logs:
httpd: page allocation failure. order:4, mode:0xd0
Call Trace:
[<ffffffff8000f696>] __alloc_pages+0x2ef/0x308
[<ffffffff80017a40>] cache_grow+0x139/0x3c7
[<...
- 568
1
vote
2
answers
801
views
swap partition alignment: is there any benefit?
On some of my Linux servers, the swap partition is misaligned. I understand how partition alignment affects performance on mounted file systems with 4k block sizes, but I am unsure if the same ...
- 13
1
vote
2
answers
1k
views
How to make Swap work? CENTOS 5.7
I've got a Centos 5.7
running Magento with nginx.
I also got there 10GB of Swap.
But the os never use it.
How can i make it work?
- 33
1
vote
2
answers
201
views
Swap on Ubuntu and CentOS
I have two questions, which is both related to a swap partition or file.
Is it possible to install either Ubuntu or CentOS without a swap configured, without tinkering?
Live CDs like Ubuntu, is there ...
- 113
4
votes
1
answer
2k
views
Server refuses to use swap partition
We are running a server with 23 cores (cpuinfo shows 22 as the highest process number) and 66 Gig RAM. The development team here is running some apps, which hogs memory.
I have observered that:
1. ...
1
vote
2
answers
235
views
Kill or revive a process based on system memory usage
Consider a system with limited memory, like a smallish VPS. Suppose there are a handful of processes that need to stay alive, and one process "P" that would be nice to have around, but is not ...
- 3,173
14
votes
1
answer
29k
views
How to free swap without rebooting (to avoid hourly alert emails)?
I get alert emails whenever swap usage is at 100%. In my case, swap usage doesn't reduce later on (even though memory is free) so I get an alert email every hour.
How can I reduce swap usage without ...
25
votes
8
answers
23k
views
Should I completely turn off swap for linux webserver?
Recently my friend told me that it is a good idea to turn off swap on linux webservers with enough memory. My server has 12 GB and currently uses 4GB (not counting cache and buffers) under peak load.
...
- 1,309
20
votes
4
answers
53k
views
How to increase swap size?
Recently, I put more ram into my server and now I have got a total of 24GB of RAM. Originally, I setup the OS to have a 2GB swap size.
/dev/sdc1 1 281 2257101 82 Linux ...
- 387
3
votes
3
answers
2k
views
top reports swap at 100%, free memory available
On RedHat 5 servers, we see top reporting swap has 0k free. vmstat shows the same amount of swap used, but no paging. We kill our only app, and top still reports 100% of swap used. If we reboot, ...
- 141
1
vote
3
answers
984
views
Socket and Swap Space
I have a system that is running out of memory and has a lot of open connections.
but my swap space is not being used up that much.
Can socket/socket file descriptors use swap space?
This is for a ...
- 293
3
votes
1
answer
1k
views
Windows Server: Prevent process swapping/paging
Is there a possibility to prevent swapping for a single process?
This process is an in-memory-database and should not be moved to virtual ram.
all other processes should still be swap-able.
I ...
5
votes
2
answers
4k
views
Should swap space be in a logical volume, or directly on disk?
What are the benefits of putting swap into a logical volume over using direct disk access?
For example, with a fresh, default install of RHEL5 or 6, a volume group is created on the default disk ...
- 18.8k